Lamar Op-Ed

More stargazing below the equator

By Paul Derrick

Posted:
03/06/2012 04:00:00 PM MST

T his column, like the previous two, comes to you from the small but fascinating country of New Zealand situated deep in the Southern Hemisphere nearly a thousand miles southeast of Australia. The natural beauty, rich diversity of scenery, and many other factors (like friendly people and no snakes or poison ivy) make this land a virtual paradise.

And for stargazers, getting to see stars, constellations, and other night sky objects in the Southern Celestial Hemisphere is a thrill. But as reported last time, I've been frustrated by cloudiness and have to keep reminding myself that the Maori - the Polynesians who first settled the islands nearly a thousand years ago - named it Aotearoa, "land of the long white cloud." And it's the rains from the clouds that give so many places in New Zealand a lush tropical rain-forest feel. Still, I'd sure like more clear nights.

One clear evening I did get to set up my wife's spotting scope (which she uses for birds) in the parking lot of a back packer (hostel) in which we were staying. Before long a small group assembled and we had a spontaneous mini-star party with folks from Canada, England, Holland and the U.S. When I pointed out Venus and Jupiter, the young man from Holland expressed surprise that the planets could also be seen from "down" here.

It gave me an opportunity to explain about the Sun's path across the sky (called the ecliptic), and how the Moon and planets also follow the same path as they move through the sky.

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And just as the Sun can be seen from all places on Earth, so can the Moon and planets. Owing to the Earth's west-to-east rotation on its axis, the Sun, Moon and planets all rise in the east and set in the west above and below the Equator.

Still, there are differences. From the Northern Hemisphere, the ecliptic tilts toward the south whereas in the Southern Hemisphere it tilts toward the north, and that can be disorienting. When we in the north see the Sun move across our sky each day, we're facing in a southerly direction, and the Sun moves left-to-right across our sky. And it's the same with the Moon and planets at night.

However from the Southern Hemisphere and facing in a northerly direction, they move right-to-left - backward from what we're used to. Even during the day this is confusing: we're accustomed to seeing the morning Sun to our left and the afternoon Sun to our right, and can almost unconsciously estimate the approximate time of day with a quick glace at the Sun's location. But here, we northerners have to consciously remember to reverse things in our mind and realize that the morning Sun will be to our right and the afternoon Sun to our left.

There is also another difference. As mentioned previously, most constellations can be seen from both the Northern and Southern Hemisphere, yet when seen from south of the Equator, they appear upside-down to us northerners. And it's the same with the Sun, Moon, and planets - they too appear upside-down. While that's not noticeable with the Sun and planets (viewed naked-eye), the full Moon's "man in the Moon" is hard to make out as he too is upside-down.

And there are yet a couple of other notable departures from what we're used to seeing. In the Northern Hemisphere, circumpolar stars and constellations rotate around the North Star (Polaris) in a counterclockwise direction whereas in the Southern Hemisphere they rotate clockwise - and they rotate around an essentially empty space in the night sky.

By chance, we have a reasonably bright star - a star we have named Polaris (the North Star) - almost straight up from Earth's North Pole. But in the Southern Hemisphere they're not so lucky as there is no bright star straight above the South Pole, and hence no South Star.

On another note, I had an interesting experience while walking in a small town. A passing stranger looked at my t-shirt, smiled big, and gave me a thumbs-up. At first I was puzzled, but quickly realized I was wearing my "Bring back Pluto" t-shirt. I guess Pluto-lovers are found around the world.

A final issue not related to stargazing is worth mentioning. After our 2001 trip to New Zealand, I was asked if I noticed water draining down basins and toilets in a reverse direction. In fact, that popular notion is a myth. A phenomenon called the Coriolis effect, caused by the rotation of the Earth, does affect large-scale systems like hurricanes which rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

But the effect is far too weak to influence the rotational flow of things in our every-day life, like water down drains, except under highly controlled laboratory situations. Other factors - like the direction from which the water enters a toilet or basin or other subtle currents within the water - determine the direction of rotation. If you make it a point to notice such things, you'll find clockwise and counterclockwise motions occur with about equal frequency.

Stargazer appears every other week in The Lamar Ledger. Paul Derrick is an amateur astronomer who lives in Waco. Contact him at 918 N. 30th, Waco, CO 76707, (254) 753-6920 or paulderrickwaco@aol.com. See the Stargazer Web site at stargazerpaul.com.